Transmitter for electromagnetic waves



Jan. 21, 1936. E MA 2,028,510

TRANSMITTER FOR ELECTROMAGNETIC WAVES Filed Oct. 21, 1932 2 Sheets-Sheet 1 Jan. 21, 1936; f K A A 2,028,510

TRANSMITTER FOR ELECTROMAGNETIC WAVES Filed Oct. 21, 1932 T 2Sheets-Sheet 2 Patented Jan. 21, 1936 'U NITE*D "'s rArs's" KraANstnr'rEn son ELECTROMAGNETIC:

WAVES Ernst Kramar, Berlin -Tempelhof, Germany, assignor to O. LorenzAktiengeselischaft, Berlin- Tempelhof, Germany Application ottom- 21,.1932, Serial No. 638,907

Germany April 19, 1932 150mm. (01. 250-11 111 radio direction flndingsystems, particularly in aerial navigation, directional antenna systemshave been employed, which radiate at. acertain angle to each other andare alternately ma- (4 nipulated in accordance with the so-calleda-nmethod. It has further been suggested to facilitate the landing ofaeroplanes by means oi! gliding-path beams. For this purpose beams ofultra-short rays are radiated obliquely upwards.

'10 The aeroplane then descends in the line of constant fleld'intensity. It has also been suggested to combine these two methods. Inaccordance with this suggestion two beams of rays are emitted at acertain angle to each other, but at=the same angle with respect to thesurface of the earth. The invention is concerned with-devices fordirection flndingmethods of this type; It employs, instead ofdirectional antenna systems wh'ch'are alternately keyed, antennaarrangements, in which reflectors or only one thereof and an exciterantenna are provided. This exciter antenna is fed continuously from thehigh ,irequency generator, and the reflector or re- 2 flectors arekeyed.

The invention is illustrated by way of example in the accompanyingdrawings. Figure 1=is a schematic elevation of an example of the device.

' Fig. 1a shows schematically an arrangement for differently modulatingthefradiated high frequency in each direction. Figures 2, 3 and 4 are.

diagrams relating .to the method 0! operation.

n-dipoleE is continuously energized by the transmitter B. On both sidesof the dipole E '35 and in hne therewith 'are arranged two dipoles Ri'and R2, which act as .reflectors; Thesereflectors are interruptedin themiddle and may beclosed by relaysMl and M2. Insteadoi' interrupting thereflectors, it is possible to provide for them tobe detuned, for.example. The re- I a lays MI and M2 are alternately energized andde-energizedby a'commutator K, whichis driven by a motor A. It is as edin the drawings that the dipole BI is opened,'that is inactive, and theg dipole m closed,t hat isaictive. Instead of the collector, a relaydevice may be employed. which is so'arranged that both relays. are keyedin parallel. and thereby the contacts of the one closed and those of theother, opened. s

. Figure 2 shows the radiationconditions, Ii. v both reflectors'Ri andR2 are opened, the horizontal' characteristic otthe energizer dipcle'Eis a circle a:--- rr only the reflector RI isclosed, then thecharacteristic 1: is obtained. It only the re- .55 flector Rl is closed,the characteristic c is obtained. If both reflectors are closed, thenthe f characteristic d is obtained. In the normal operation forradio-beacon purposes the characteristic d can be dispensed with. Forcertain purposes, however, characteristics of this type are 5 desirable.

,This arrangement'which preferably operates with ultra-short waves, isquite suiilcient for the purpose in view, that is the directionalcharacteristics are sufficientlyinten'se, as the point of in- 10tersection' of two characteristics is utilized, for example, the pointofintersectionPl of b and c.

alternately keyed. A single reflector is quite suiflcient for a simpledevice.

'Figure 3 shows the influence of the between energizer E and}, for thesake 1 sim- 20 plicity, a single reflector R. The distance between E andR for the characteristic e amounts to x/5,for f M3, and for g M2, when7L is the wavelength. r

It is thus found that by increasing this distance to M2 the directionalcharacteristic is intensifled in a direction perpendicular to the linepassing through the energizer E and the reflector R.

According to Figure 4, similar effects :may be 0 obtained by varying thelength 01- the reflector it with respect to the length (ii/2Y0!theenergizer dipole E. The length ratio, however, is concerned with theformation: or maxima which extend oppositely to the intendeddirection.The characteristic 'h, corresponds to I an arrangement in which, withthe same distance between theenergizenE and-reflector R as before,

the length of the reflector R is smaller than M2. The characteristic 2'applies for M2, that is for a reflector which is the same length as theenergizer, and characteristic k for an arrangement in which. thereflector is longer than the energizer :and especially with ultra-shortwaves. The presstance aoaaaio ent invention avoids keying the highfrequency radiation from said main antenna, and means for current sinceonly the reflector or reflectors are influenced. The circuits of therelays MI and M2 carry only direct current er. low frequency alternatingcurrent and can be easily protected against high frequency, for exampleby choke arrangements. The conductors to the relays may also consist ofresistance wire, in order to prevent the passage of high frequencycurrents. The-invention may also be employed in arrangements inwhichinstead of transmitting signals-according to the a-n-method or thelike, the radiated high frequency ismodulated with different modulationfrequencies, viz. at a particular frequency-in each direction. In thiscase, in accordance withthe invention, the carrierfresudclnly renderingthe reflection antennae alternately effective and ineffective so thatonly one reflection antenna is-eflective at a time, said ing a mainantenna, a high frequency generator quency, which is\ conveyed to theenergizer antenna, is modulated differently in the same rhythm in whichthe reflectors arekeyed. In this manner the characteristic modulationfrequency is transmitted in the corresponding angular space. Such amodulating arrange t is shown in lj'ig. 1 wherein the high frequency ofthe transmitter S is modulated at one frequency h in one direction and.ate-frequency f: in the other direction, a switch at being provided tooperate in rhythm withcommutator K so as to connect the appropriatemodulating frequency with transmitter S as the respective reflectingantenna: R1- and R2 are keyed. v

- The keying of the reflector may be eflectechby the means A, K, Ml, M2shown in Figure 1, and a further collector or relay arrangement-providedV for controlling the alternate modulation of the transmitter at twomodulation frequencies, or a two-frequency machine may be used which isprovided with a cam disc arrangement for the actua tion of contactscontrolling modulation frequencies. What is claimed is:

1. A radio transmitting arrangement comprising a main antenna, a highfrequency generator coupled thereto,. a reflecting antenna on eitherside of said main antenna and spaced in line therewith a half wavelengththerefrom, and means for abruptly rendering said reflecting antennaaalternately effective and ineffective so that the supply of the one isineffective whilst the other is efl'ective to reflect the radiation fromsaid main antenna.

2; A radio transmittingarrangement compriscoupled thereto, a reflectingantenna on either side of said main antenna and spaced therefrom in linetherewith, means for abruptly rendering said reflecting-antennaealternately eifective and ineffective so that one is ineffective whilstthe other is effective to reflect the radiation from said main antenna,sources of modulating signals of two different frequencies, and meansfor modulatingthe high frequency from the main antenna in accordancewith the signal of one of said modulatingfrequencies whilst one of saidreflecting antenna is eil'ective, and by signal of the other of saidmodulating frequencies whilst the, other of 'said reflecting antenna: iseffective.

6. A radiotransmittin'g arrangement comprisingga main antenna, a highfrequency generator coupled thereto, a reflecting antenna on either sideof said main antenna. and spaced therefrom in line therewith, means forabruptly rendering said'reflecting antenna alternately efl'ective andineffective so that one is ineffective whilst the other is effective toreflect the radiation from said main antenna thereby to produce a zoneof equal -fleld intensity, and means for modulating the high frequencyby a signal whilst one of the reflecting antenna: is effective and by acomplemental signal whilst the other reflecting antenna is effective sothat said signals combine to form a continuous signal within the equalfield intensity zone. I

'7, A radio transmitting arrangement comprising a main antenna. a highfrequency generator coupled thereto, a reflecting antenna on either sideof said main antenna and spaced therefrom in line therewith, means forabruptly rendering said reflecting antenna alternately'effective andineffective so that one is ineffective whilst the other is effective toreflect the radiation from j said main antenna thereby to produce azoneof equal fleld intensity, and means for modulating ing an energizerdipole having a length equal to a .1

half wavelength, a high frequencygenerater cou-- pied thereto, .ftworeflector dipoles. of greater length than said energizer dipole andspaced therefrom on either side thereof and in line therewith adistance-equal to a half wavelength,

and means for abruptly rendering said reflecting dipoles alternatelyeffective and ineffective each being ineffective whilst the other iseflective.

3.. A radio transmitting arrangement comprising an energizer dipolehaving a length equal to a half wavelength, a high frequency generatorcoupled thereto, two reflector dipoles of greater.

length than saidenergizer dipole and spaced therefrom on either sidethereof and in line therewith a distance equal to a half wavelength,.-and

means for alternately opening and closing said;

reflector dipoles so that whilst one is effective the other isineffective to reflect the radiation from said energizer dipole.

4. A radio transmitting arrangement .compris; ing a main antenna, a highfrequengy generator coupled ,thereto, a plurality ofreflec'tion antennaeco-operating with saidmainantenna'when effective, .to reflect andthereby make-directive the 8. A radio transmitting'arrangement compris-"ing a main antenna, a high frequency generator coupled thereto,-areflecting antenna on either .side of said main antenna and spacedtherefrom.

inline therewith, and means for abruptly rendering said reflectingantennae alternately effective and ineffectiveso that one is ineffectivewhilst the. other is effective to reflect the radiation from.

said main antenna.

. 9. Aradio transmitting arnangement compris ing, a main antenna, a highfrequency generator coupled thereto. a reflecting antenna on either sideof said main antenna. means for rendering said reflecting antennaalternately effective and ineffective so that -oneis ineffective whilstthe otheris effective to reflect the radiation from said antenna, saidreflecting antenna: being spaced y from the main antenna an odd multipleof a half wavelength therefrom and in such relation thereto that aportion, of the area of the reflected radiation from one reflectingantenna also forms a portion of the area of the reflected radiation fromthe other reflecting antenna whereby said alternate operation of saidreflecting antennae produces a zone of equal field intensity in saidcommon area.

10. A radio transmitting arrangement comprising, an energizer dipolehaving a length equal to spect to said energizer dipole that there isproduced a zone common to the reflected radiations from the tworeflector dipoles, and means for abruptly rendering said reflectordipoles alternately effective and ineflective each being ineffectivewhile the other is effective thereby to produce in said zone a fleld ofequal intensity.

11. A radio transmitting arrangement comprising, a main antenna, a highfrequency generator coupled thereto, a reflecting antenna on either sideof said main antenna and so disposed with respect thereto as to producea zone common to the radiations reflected from said reflecting an-Qtenure, means for rendering said reflecting an-.

tenna alternately effective and ineffective so that one is ineffectivewhilst the other is efiective to reflect the radiations from said mainantenna thereby to produce in'said zone a fleld of equal intensity, andmeans for modulating the high frequency in accordance with one signalwhilst'one of the reflecting antenna: is eflective'and in accordancewith a difl'erent signal whilst the other reflecting antenna iseffective. 3

12. A radio transmitting arrangement compris ing, a main antenna, a highfrequency generator coupled thereto, a reflecting antenna on either,side of said main antenna, means for rendering said reflecting antennaealternately eflective and inefiective so that one is ineflective whilstthe other is eflective to reflect the radiation from said antenna, saidreflecting antenna being spaced from the main antenna and in suchrelation thereto that a portionof the area of the rea flected radiationfrom one reflecting antenna also forms a portion of the area of'thereflected radiation from the other reflecting antenna whereby saidalternate operation of said reflecting antenme produces a zone of equalfleld intensity in said common area.

13. A radio transmitting arrangement comprising, an energizer dipolehaving a length equal to a half wavelength, a high frequency generatorcoupled thereto; two reflector 'dipoles of greater length than saidenergizer dipoles and spaced therefrom on either side thereof and sodisposed with respectto said energizer dipole that there isv produced azone common to the reflected radiations from the two reflector dipoles,and means for abruptly rendering said'reflector dipoles alternatelyeffective and ineffective each being ineflective while the other iseffective thereby to produce in said zone a fleld of equal intensity.

14. A radio transmitting arrangement compris in a main antenna, a highfrequency generator coupled thereto, a reflecting antenna on eitherthereby to produce in said zone a fleld of equal intensity. 4

15. A radio transmitting arrangement comprising a main antenna, a highfrequency generator coupled thereto, a reflecting antenna at one sideoi. said main antenna, continuously operable means for rendering saidreflecting antenna alternately effective and ineffective, saidreflecting antenna being in such relation to the main antenna thata'portion of the'area of the reflected radiation also forms a portion ofthe area of the in radiation from the main antenna whereby the alternateoperation of said reflecting antenna ERNST KRAMAR.

